-- You know the area of a rectangle, and you know its width.
Let's pause here, and gather up a few tools to do the job with.
The tools you'll need are the things that you know about rectangles.
Definitions of the area and perimeter of a rectangle would be very helpful.
=> Area of a rectangle = (length) x (width)
=> Perimeter of a rectangle =
(length+width + length+width) = 2 (length+width)
You know all the numbers in both of these formulas, except the length.
Can you think of a way to find it, using the numbers that you do know ?
Take the area formula . . . . . Area = (L) times (W)
Put in the numbers you know: 25 m² = (L) x (2.5 m)
Divide each side by 2.5 m : (25 m²) / (2.5 m) = L
10 m = L
Now you know both 'L' and 'W'.
so ...
Time to go directly to the perimeter formula:
Perimeter = 2 (L + W)
= 2 (10m + 2.5m)
= 2 (12.5 m)
= 25 m